1. Field of the Invention
This invention relates, generally, to wrenches; more particularly, it relates to a wrench having jaws that may be locked into any desired position relative to one another by advancing a screw member.
2. Description of the prior art
Lever-actuated pivoted jaw wrenches are shown in U.S. Pat. Nos. 1,862,817 to Eifel (1932); 2,201,918 to Petersen (1940), 2,280,005 to Petersen (1942), 2,489,895 to Kash (1949), 2,496,308 to Pugh and others (1950), 2,589,511 to Redmon (1952) and 4,478,114 to Arens (1984).
The devices of the prior art perform their intended function, but are characterized by complex constructions which are not economical to manufacture.
The art teaches the use of a construction often referred to as an "overcenter" or "cam over center" construction. In such type of wrenches, a movable handle member is pivoted about a point such that once it has pivoted past the point, it cannot thereafter be forced open at the point where it meets its unpivoted counterpart. Essentially, the fulcrum of the lever (the movable handle) is positioned off center so that, once the lever is pivoted therepast, the location of the fulcrum prevents facile return of the lever (handle) to its original position
Overcenter designs have utility, but, again, tend to be structurally complex. Accordingly, there is a need for a wrench of simple, non-overcenter design that operates as well as an overcenter design.
The prior art neither teaches nor suggests new designs that could provide an elegantly constructed wrench capable of performing as well as the prior art tools.